Syndecan-1 in the Tumor Microenvironment

High expression of SDC1 in stromal cells is associated with good prognosis in colorectal cancer

We have previously reported that patients with high Syndecan 1 (SDC1) expression in colorectal cancer (CRC) cells have a favorable prognosis, and we also found that stromal cells showed upregulation of SDC1, but the clinical significance is unclear. The expression of SDC1 in the stroma cells was assessed by immunohistochemistry using a tissue microarray comprising representative cores from 513 CRC patients. The correlation between the expression of SDC1 in the stroma cells and the clinicopathological features of patients was analyzed. The data showed that the expression of SDC1 in the stroma cells was correlated with the degree of differentiation ( P  = 0.012) and tumor location (up or down) ( P  = 0.005). Also, CRCs patients with high expression of SDC1 in the stromal cells have a good prognosis ( P  = 0.0369). Accumulating evidence indicates that SDC1, whether in tumor cells or stromal cells, plays a tumor-suppressor role in CRCs.

Matrix proteoglycans in tumor inflammation and immunity

Cancer immunoediting progresses through elimination, equilibrium, and escape. Each of these phases is characterized by breaching, remodeling, and rebuilding tissue planes and structural barriers that engage extracellular matrix (ECM) components, in particular matrix proteoglycans. Some of the signals emanating from matrix proteoglycan remodeling are readily co-opted by the growing tumor to sustain an environment of tumor-promoting and immune-suppressive inflammation. Yet other matrix-derived cues can be viewed as part of a homeostatic response by the host, aiming to eliminate the tumor and restore tissue integrity. These latter signals may be harnessed for therapeutic purposes to tip the polarity of the tumor immune milieu toward anticancer immunity. In this review, we attempt to showcase the importance and complexity of matrix proteoglycan signaling in both cancer-restraining and cancer-promoting inflammation. We propose that the era of matrix diagnostics and therapeutics for cancer is fast approaching the clinic.

Weighted Gene Co-Expression Network Analysis (WGCNA) Reveals the Functions of Syndecan-1 to Regulate Immune Infiltration by Influenced T Cells in Glioma

Our previous studies shown that syndecan-1 (SDC1) may be a novel class of biomarkers for the diagnosis and treatment of glioma, but its specific roles and the in-depth molecular mechanism remain elusive. Here, we used Estimation of STromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) algorithms and single-sample Gene Set Enrichment Analysis (ssGSEA) algorithms to evaluate the immune score of tumor samples and quantify the relative infiltration of immune cells in the tumor microenvironment (TME), respectively, in different data sets obtained from the Chinese Glioma Genome Atlas and The Cancer Gene Atlas. Next, we calculate the correlation of the immune score and immune cells with SDC1, respectively. To identify the specific process regulated by SDC1, the differentially expressed genes (DEGs) analysis between the high and low expression of SDC1 of glioma samples were used to discover the hub genes through Weighted Gene Coexpression Network Analysis (WGCNA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed cardinal biological processes and pathways involved in genes and tumor grade correlation and survival analysis verified its significance in glioma. The results show that SDC1 is associated with the immune infiltration of glioma in the TME, especially activated CD4+T cells and CD8+T cells. The three data sets filter 8,887 DEGs, the genes in the blue modules were selected as hub genes in WGCNA. GO and KEGG analysis found eight genes in the blue modules involved in antigen processing and presentation in T cells in glioma. Kaplan-Meier estimator and log-rank test statistic determined that the introduced genes are associated with poor prognosis in glioma. Protein-protein network interaction analysis showed that SDC1 may regulate antigen processing and presentation through CTSL or CD4 in glioma. Finally, this study provided insights and clues for the next research direction of SDC1 and identified the key pathways and genes that might participate in the immune escape of glioma. These results might provide a new insight on the study of immune infiltration of glioma in the future.

The NF-κB-regulated miR-221/222/syndecan-1 axis restores intestinal mucosal barrier function in radiation enteritis

PURPOSE

Radiation enteritis (RE) is the most common complication of pelvic radiotherapy, but proven therapies are lacking. Barrier function defects are closely associated with numerous inflammatory disorders. In this study, we investigated whether barrier dysfunction contributes to RE and whether syndecan-1 (Sdc1) protects intestinal barrier function in RE. The mechanism was also elucidated.

MATERIALS AND METHODS

Blood, urine, and tissue samples were collected from 21 patients with cervical cancer who experienced RE during radiotherapy and used to detect inflammatory responses and barrier function. The role of Sdc1 in barrier function was examined in cultured fetal human colon (FHC) cells exposed to radiation and an induced mouse RE model. Barrier function was determined by zonula occludens (ZO)-1 and occludin expression, transepithelial electrical resistance (TEER), and FITC-dextran (FD4) flux. The role of the nuclear factor (NF)-κB-P65 pathway was detected by Western blotting and chromatin immunoprecipitation. The role of miR-221/222 was assessed by real-time PCR and luciferase reporter assays.

RESULTS

Patients with RE exhibited obvious pathological and ultra-microstructural inflammatory injury and barrier disruption in the intestinal mucosa, as well as higher serum lipopolysaccharide (LPS), LPS-binding protein, and cytokine levels and a higher urine lactulose/mannitol ratio. Sdc1 overexpression in irradiated FHC cells reversed TEER suppression, repressed FD4 flux, and upregulated ZO-1 and occludin expression. Exogenous low-molecular-weight heparin supplementation in RE mice ameliorated the activity of enteritis and barrier defects. Mechanistically, irradiation-activated P65 increased the transcription of miR-221/222 via direct binding to their promoter regions, and miR-221/222 then post-transcriptionally suppressed the Sdc1 gene by binding to its 3'-untranslated region.

CONCLUSIONS

Sdc1 protects barrier function and controls inflammation during RE under transcriptional regulation by the NF-κB pathway and miR-221/222. The network including NF-κB, miR-221/222, and Sdc1 is important in the pathogenesis of RE. Sdc1 might represent a therapeutic target for novel anti-RE strategies.

Tumor-Associated Extracellular Matrix: How to Be a Potential Aide to Anti-tumor Immunotherapy?

The development of cancer immunotherapy, particularly immune checkpoint blockade therapy, has made major breakthroughs in the therapy of cancers. However, less than one-third of the cancer patients obtain significant and long-lasting therapeutic effects by cancer immunotherapy. Over the past few decades, cancer-related inflammations have been gradually more familiar to us. It’s known that chronic inflammation in tumor microenvironment (TME) plays a predominant role in tumor immunosuppression. Tumor-associated extracellular matrix (ECM), as a core member of TME, has been a research hotspot recently. A growing number of studies indicate that tumor-associated ECM is one of the major obstacles to realizing more successful cases of cancer immunotherapy. In this review, we discussed the potential application of tumor-associated ECM in the cancer immunity and its aide potentialities to anti-tumor immunotherapy.

Syndecan-1 (CD138), Carcinomas and EMT

Cell surface proteoglycans are known to be important regulators of many aspects of cell behavior. The principal family of transmembrane proteoglycans is the syndecans, of which there are four in mammals. Syndecan-1 is mostly restricted to epithelia, and bears heparan sulfate chains that are capable of interacting with a large array of polypeptides, including extracellular matrix components and potent mediators of proliferation, adhesion and migration. For this reason, it has been studied extensively with respect to carcinomas and tumor progression. Frequently, but not always, syndecan-1 levels decrease as tumor grade, stage and invasiveness and dedifferentiation increase. This parallels experiments that show depletion of syndecan-1 can be accompanied by loss of cadherin-mediated adhesion. However, in some tumors, levels of syndecan-1 increase, but the characterization of its distribution is relevant. There can be loss of membrane staining, but acquisition of cytoplasmic and/or nuclear staining that is abnormal. Moreover, the appearance of syndecan-1 in the tumor stroma, either associated with its cellular component or the collagenous matrix, is nearly always a sign of poor prognosis. Given its relevance to myeloma progression, syndecan-1-directed antibody—toxin conjugates are being tested in clinical and preclinical trials, and may have future relevance to some carcinomas.